This invention relates to an instrument and method for removing a cam lesion from the neck of a femur.
Femoral acetabular impingement is a condition of too much moving contact between the femur and the rim of the acetabulum during movement of the hip joint. There are two forms of contact between the neck and head of the femur and the acetabulum under the category of femoral acetabular implant. One form is called cam impingement and the other pincer impingement. The cam form occurs when the femoral head and neck is shaped so that it impinges on an otherwise normal rim of the acetabulum. This abnormal contact between the head and neck of the femur and the acetabular rim generates pain. The pincer form of impingement occurs when the rim of the acetabulum is enlarged to provide excessive coverage of the femoral head so that the rim impinges on a normally shaped head or neck of the femur upon movement of the hip joint. Again this contact causes pain in the patient. Often these two problems occur simultaneously. Usually the deformities in both the neck and head of the femur and of the rim of the acetabulum face anteriorly in the anterior-superior quadrant.
Because the area of contact between the bone of the neck and head of the femur and the acetabular cartilage occurs over a wide area, usually the cartilage area involved in cam impingement is larger than in pincer impingement.
Cam impingement can be caused by an osseous bump or lesion on the femoral head-neck junction. In the past, arthroscopic debridement of the femoral neck has been performed to remove cam lesions. Alternately, a surgical procedure in which an anteriolateral bump is removed with an osteotome is used to restore the concave contour of the head-neck junction. In addition, the femoral head may be rounded by smoothing the surface with a burr. In either of these procedures the resections are performed by hand without the use of any instrumentation designed to facilitate the quick and accurate removal of bone tissue.